1. Field of the Invention
The invention generally relates to Physical Downlink Control Channel (PDCCH) monitoring, and more particularly, to PDCCH monitoring for a downlink assignment reception and an uplink grant reception when the User Equipment (UE) has a Semi-Persistent Scheduling (SPS) Cell Radio Network Temporary Identifier (C-RNTI).
2. Description of the Related Art
With growing demand for ubiquitous computing and networking, various wireless technologies have been developed, such as the Wireless Local Area Network (WLAN) technologies, including the Wireless Fidelity (WiFi) technology, Bluetooth technology, and the ZigBee technology, etc., as well as cellular technologies including Global System for Mobile communications (GSM) technology, General Packet Radio Service (GPRS) technology, Enhanced Data rates for Global Evolution (EDGE) technology, Wideband Code Division Multiple Access (WCDMA) technology, Code Division Multiple Access 2000 (CDMA2000) technology, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) technology, Worldwide Interoperability for Microwave Access (WiMAX) technology, Long Term Evolution (LTE) technology, Time-Division LTE (TD-LTE) technology, and LTE-Advanced technology, etc.
Taking the LTE technology as an example, a feature called Semi-Persistent Scheduling (SPS) has been proposed to reduce control channel overhead for applications that require persistent radio resource allocations such as Voice over Internet Protocol (VoIP). For the LTE technology, both downlink (DL) and uplink (UL) are fully scheduled since the DL and UL traffic channels are dynamically shared channels. This means that the PDCCH must provide access grant information to indicate which user device(s) should decode the Physical Downlink Shared Channel (PDSCH) in each subframe and to indicate which user device(s) is(are) allowed to transmit on the Physical Uplink Shared Channel (PUSCH) in each subframe. Without SPS, every DL or UL Physical Resource Block (PRB) allocation must be granted via an access grant message on the PDCCH. This is sufficient for most bursty best-effort types of applications which generally have large packet sizes and thus typically only a few users must be scheduled in each subframe. However, for applications that require persistent allocations of small packets (e.g. VoIP), the access grant control channel overhead can be greatly reduced with SPS.